We recently got an exclusive sampling of Arctic Cat’s new 2015 XF 6000 C-TEC and can happily report the new 600cc DSI mill has found another happy home in this sled.
The whole premise of the DSI slot injection mill was to get as close to DI’s precision fuel management as possible without actually using a cylinder head injector to get fuel into the combustion chamber when the rising piston closes the exhaust port.
The side-mounted injector on the C-TEC shoots right through the cylinder wall and not into the transfers like on current SDI systems. This difference is significant.
The injector is aimed at the piston dome and squirts fuel intermittently up to about 7000 rpm. This angled orientation and on/off sequence means there’s little (if any) unburned fuel escaping out the exhaust port.
In fact the injector is precisely timed and aimed to keep fuel from exiting the combustion chamber until the exhaust port is closed. This description puts DSI at a higher level of precision than typical SDI systems.
When the throttle is whacked open and RPMs pass the 7K mark the injector stays on full time shooting fuel on top of and underneath the piston (through the piston slot) to be scavenged up the transfers with the incoming air.
The always-on injector’s mixed fuel coming up the transfers is contained effectively by the expansion chamber’s reverse pulse – which is at its sweet spot at 7000 RPM and above.
What does all this mean? Our 2014 El Tigre 6000 has carded the highest non-DI 2 stroke mileage we’ve seen with a legit 20 MPG (US Gallon) and regularly exceeding 16 MPG on hard pulls. The motor sips oil as well as a result of its electronic stepper pump system and is the 600 to beat in MY14.
The XF 137 chassis is as happy with the light 600 DSI as the 129-inch ZR platform.
There’s a hint of understeer common in all Arctic Cat’s 137-inchers using dual staggered carbides. To correct this, we’ve installed 6-inch single runner carbides instead and have seen the understeer erased.
The 2015 XF’s ride quality is improved substantially by an new valve code spec for the rear arm Fox damper and a move to lighter factory air pressure settings on the Fox air shocks up front.
All in all we think this is one sweet X-over ride for MY 2015. Great power sets the new standard in the 600-class with excellent ride quality in a trail biased 137-inch chassis.